Journal of biophotonics最新文献

Epicardial catheter ablation is necessary to address ventricular tachycardia targets located far from the endocardium, but epicardial adipose tissue and coronary blood vessels can complicate ablation. We demonstrate that catheter-based near-infrared spectroscopy (NIRS) can identify these obstacles to guide ablation. Eighteen human ventricles were mapped ex vivo using NIRS catheters with optical source-detector separations (SDSs) of 0.6 and 0.9 mm. A logistic regression model trained from manually labeled spectra achieved mean area under the receiver operating characteristic curve (AUROC) of 0.907 (0.6 mm SDS) and 0.911 (0.9 mm SDS) in binary adipose detection. Novel optical indices for adipose detection were also proposed, achieving AUROCs of 0.881 (0.6 mm SDS) and 0.873 (0.9 mm SDS), while a blood-specific optical index achieved AUROC of 0.859 for vessel detection (0.9 mm SDS). These results suggest that catheter-based NIRS can detect adipose tissue and coronary vessels to improve efficacy and safety of epicardial ablation.

The brain, as a vital part of central nervous system, receives approximately 25% of body's blood supply, making accurate monitoring of cerebral blood flow essential. While fNIRS is widely used for measuring brain physiology, complex tissue structure affects light intensity, spot size, and detection accuracy. Many studies rely on simulations with limited experimental validation. In this study, we used real adult skulls and agar to create a mimic model, building a transmission optical system with 13 wavelength filters and varying agar thicknesses. Peak intensity of transmitted light and size of scattered spot were measured at different wavelengths, and transmittance, total attenuation coefficient, and spot diameter enlargement of cranial mimics at different wavelengths were obtained. Results showed wavelengths below 550 nm struggled to penetrate the skull, while those above 700 nm penetrated deeper and diffused more. This suggests that short wavelengths capture epidermal PPG signals, whereas longer wavelengths detect both epidermal and intracranial signals.

Availability of a suitable tool for carrying out non-invasive measurement of Raman signatures in situ, from biological tissues having low Raman cross section is a clinically unmet need faced with manifold challenges. A Raman probe can prove to be an invaluable component of clinical Raman diagnostic systems. We present development of a Raman probe capable of measuring artefact free Raman spectra of biological tissues in situ. The developed probe uses a single lens for simultaneous illumination and collection of the Raman signal backscattered from the sample surface. This configuration ensures not only maximum overlapping of the illumination and collection volumes, ultimately leading to optimal throughput but also reduces the fiber-induced artefacts. The results show a superior performance of the developed Raman probe in measuring the Raman signatures from biological samples having lower Raman cross-sections, compared to that of the two commercially available Raman probes.

In this study, we aim to validate the analytical Cramer-Rao lower bound (CRLB) equation for determining attenuation coefficients using a 1310 nm Optical Coherence Tomography (OCT) system. Our experimental results successfully confirm the validity of the equation, achieving unprecedented precision with a standard deviation below 0.01 mm^-1 for intralipid samples. Furthermore, we introduce a systematic framework for attaining high precision in OCT attenuation measurements.

This study examines the effects of pulsed wave photobiomodulation (pwPBM) on the osteogenic differentiation of stem cells from the apical papilla (SCAP). Using 810 nm near-infrared (NIR) light with 300 Hz pulses and a 30% duty cycle, pwPBM was applied at a total energy density of 750 mJ/cm². Osteogenesis was evaluated through both in vitro and in vivo analyses. In vitro experiments demonstrated significant enhancement of alkaline phosphatase (ALP) activity, along with upregulation of key osteogenesis-related genes and proteins, as confirmed by real-time polymerase chain reaction (PCR) and Western blot analyses. In vivo, histological assessments following SCAP transplantation revealed increased bone tissue formation, further corroborated by osteocalcin staining. These findings underscore the potential of pwPBM as an innovative and effective tool for dental tissue regeneration and engineering.

Zerumbone is a sesquiterpene phytochemical with cytotoxic activity against cancer. This study aimed to evaluate the effect of zerumbone on cell viability by WST-1 test, apoptosis by TUNEL, lipid peroxidation markers (malondialdehyde, MDA, and 4-hydroxynonenal, HNE) by using assay kits, and biomolecular changes by ATR-FTIR spectroscopy in A549 cells. After zerumbone (0-100 μM) incubation for 24, 48, and 72 h, the number of TUNEL-positive cells was found to be higher in zerumbone-treated cells than in controls, in consistent with cell morphology results. MDA levels increased significantly, although HNE levels increased non-significantly in zerumbone-treated cells. Spectral analyses revealed that the zerumbone-treated groups had higher levels of total saturated and unsaturated lipids as well as comparatively shorter-chain lipids. On the contrary, reduced RNA/DNA ratio, total nucleic acid, and protein content were found in zerumbone-treated groups. Consequently, zerumbone-induced apoptosis was accompanied by increased aldehyde products during lipid peroxidation as well as biomolecular alterations.

The use of photoacoustic brain imaging for hemorrhage detection holds significant clinical importance. This study focuses on the performance of sensitivity and detection capabilities of a single-element scanning system, considering the remarkable signal-to-noise ratio of photoacoustic signals generated by a single-element transducer. By employing blood vessel-like phantoms and ex vivo brain phantoms, we demonstrated the superior efficacy of the single-element scanning method over the transducer array system in the context of brain hemorrhage detection. This research highlights the potential for enhancing hemorrhage detection sensitivity through careful design and optimization of the proposed method, thereby increasing its viability for clinical application.

A challenge in neuroimaging is acquiring frame sequences at high temporal resolution from the largest possible number of pixels. Measuring 1%-10% fluorescence changes normally requires 12-bit or higher bit depth, constraining the frame size allowing imaging in the kHz range. We resolved Ca²⁺ or membrane potential signals from cell populations or single neurons in brain slices by acquiring fluorescence at 8-bit depth and by binning pixels offline, achieving unprecedented frame sizes at kHz rates. In hippocampal slices stained with the Ca²⁺ indicator Fluo-4 AM, we resolved transients at 2 kHz from large frames. Along the apical dendrite of a layer-5 pyramidal neuron, we measured Ca²⁺ signals associated with a back-propagating action potential at 10 kHz. Finally, in the axon initial segment of the same cell type, we recorded an action potential at 40 kHz by voltage-sensitive dye imaging. This approach unlocks the potential for a range of imaging measurements.

Genetic information sensors play a pivotal role in the biomedical field. The detection of deoxyribonucleic acid (DNA) is achieved experimentally using an optical microfiber interferometric sensor, which operates based on an ion-regulation sensitivity enhancement mechanism. The optical microfiber is fabricated by drawing optical fiber into a diameter of less than 10 μm via the melting and tapering technique. Leveraging the characteristics of monovalent cations can effectively promote the folding of G-rich single-stranded DNA (ssDNA) into stable G-quadruplex structures, enabling the detection of specific sequences of ssDNA at low concentrations. The results show an improvement of the linear detection range by 3 orders of magnitude, and with the introduction of the ion-regulation sensitivity enhancement mechanism, the limit of detection (LOD) value is 1.07 × 10^-15 M. This optical microfiber interferometric sensing architecture is characterized by its simplicity and high sensitivity, positioning it as a formidable tool for diverse biosensing and analytical applications.

The article describes a technique for digital holographic reconstruction of complex amplitude fields in diffuse blood facies using laser polarization-interference phase scanning to isolate a single scattered component of the object field. This method serves as the basis for developing algorithms for Mueller-matrix reconstruction of linear and circular birefringence parameters in the polycrystalline architectonics of blood facies. Statistical (central moments of the 1st-4th orders) and multifractal analyses (fractal dimension spectra) are applied to study the optical anisotropy maps of polycrystalline networks during blood dehydration. The study explores a practical application in the differential diagnosis of blood loss volume, identifying higher-order central moments (skewness, kurtosis) as sensitive markers. The method achieved a maximum accuracy of 92.9% in differentiating blood loss volume.